icy_draw: Windows default zoom in/out hotkeys are shared with changing the size of the interface

[TheGreenHerring]

Version used: icy_draw_windows_0.3.0 from build #77

In Windows, the default hotkeys assigned to zooming in and out from the menu are Ctrl+Plus and Ctrl+Minus. However, these same hotkeys are also used to change the size of icy_draw's interface. It is possible to change the zoom in/out hotkeys to other keybinds, but as far as I can tell, there is no option to change the hotkeys for changing the size of the program's interface.